At present, with the population aging in China, the aged people are increasing gradually. For these aged people, especially those suffering from mobility problems caused by disease, they have more and more difficulties in walking since their physical functions are gradually decreasing. In this case, there is an increasing demand for a portable and sturdy walker which is convenient to park. However, most walkers on the market are only able to be folded only once, causing huge sizes, so these walkers are not convenient for carrying, transportation and storage. In order to address the above problem, some walkers that can be folded secondly are presented. However, for such walker, the secondary folding generally requires the user to bend down and squat to adjust a switch to do the folding operation. Such action is very difficult for normal users, especially aged people who have difficulties in walking, and meanwhile, there is a potential safety problem.